Soy Sauce: To Refrigerate or Not Refrigerate

On my huge bottle of Kikkoman soy sauce it says very clearly: "Refrigerate after opening." And yet I don't. My Asian friend, an amateur chef, never does. I go to Chinese restaurants and there is soy sauce sitting out on every table.

So what's the deal? Are you supposed to refrigerate or not? I did a little research and discovered that soy sauce is fine at room temperature. It's just that it will keep its flavor and freshness longer when refrigerated.